1. Technical Field of the Invention
The present invention relates in general to communication establishment in communication networks and, in particular, to a system and method for minimizing the number of messages transmitted to establish a communication in telecommunications networks.
2. Description of Related Art
Mobile wireless communication is becoming increasingly important for safety, convenience, and simply enjoyment. One prominent mobile communication option is cellular communication. Cellular phones, for instance, can be found in cars, briefcases, purses, and even pockets. To maximize the enjoyment of cellular phones, however, cellular systems must be optimized.
Cellular systems are composed of not only wireless, but also wireline, communication channels. Wireline communication channels include connections both within the cellular network and those that extend beyond the cellular network to connect to the public switched telephone network (PSTN). Due to the prominence of the wireline portions of the cellular network, optimizing cellular systems requires efficient utilization of the wireline connections. One measure of efficiency is cost minimization, so a system and method that reduces the cost of cellular service improves efficiency.
It should be understood that the various nodes in wireline networks are interlinked. The links enable networks as a whole and the individual nodes to communicate with one another. Nodes can be, in a Global System for Mobile Communications (GSM) network for example, well-known components according to the GSM standard such as a Gateway Mobile Switching Center (GMSC), a Home Location Register (HLR), or a Mobile Switching Center/Visitor Location Register (MSC/VLR). Communication between nodes within the telecommunications system is preferably accomplished through Signaling System No. 7 (SS7) protocols, as is understood to those skilled in the art. One application protocol for use in mobile SS7 networks is the Mobile Application Part (MAP). MAP is responsible for providing mobility services such as Location Management Services and Subscriber Management Services.
The MAP protocol standard, like most standards, has evolved since its inception. Unfortunately, not all nodes employing SS7 technology are immediately updated with the latest MAP protocols. It is generally thought that the most advanced protocol in common between two communicating nodes should be used in an inter-nodal communication since this provides the greatest functionality and communication features. To that end, a first node may attempt to communicate with a second node with a more recent, e.g., a higher numbered, version than the second node can understand, an example of which is shown in FIG. 1.
With reference now to FIG. 1, a sequence diagram, generally designated by the reference numeral 100, is illustrated. The sequence diagram 100 represents a negotiation between two GSM network nodes utilizing MAP protocol. A negotiation typically begins a communication between the two nodes and is designed to establish the highest, mutually-understood MAP version level. Each communication corresponds to a dialogue type, otherwise known as an Application Context (AC) when using MAP.
In FIG. 1, for example, a sender 110 is a node that has been updated to a third protocol version and is trying to communicate with a receiver 120, which only understands a second, older protocol version. In conventional systems, the sender 110 attempts to start the communication with a message 130 using the aforementioned third protocol version of the communication program (Protocol #3). The receiver 120, however, understanding only the second protocol version of MAP (Protocol #2) and no higher, responds with a message 140 instructing the sender 110 to stop the communication because the message 130 was not understood.
With respect to the message 140 that is transmitted from the receiver 120 to the sender 110, the contents of the message 140 explicitly inform the sender 110 that the desired communication is only supported in the second protocol version. Hence, the sender 110 then falls-back to the second protocol version and reattempts to start the desired communication using the second protocol version in a message 150, i.e., Protocol #2 in this example. The receiver 120, configured for this second protocol version, understands the attempt and responds accordingly with a message 160 permitting the desired communication to continue with the second protocol version.
Alternatively, the receiver 120 may only understand the first protocol version of MAP (Protocol #1). In this instance, the message 140 implicitly informs the sender 110 that only the first protocol version is supported. The message 140 essentially responds by relaying that it does not understand 130 at all. The sender 110 can then determine implicitly that only the first protocol version is supported. Thus, the sender 110 then falls-back to the first protocol version, i.e., the oldest or most basic version, and reattempts to start the desired communication using the first protocol version (Protocol #1) in the message 150. The receiver 120 then responds with the message 160 permitting the desired communication to continue with the first protocol version.
Although messages in the MAP protocol provide either an explicit or an implicit indication of the highest protocol version that is understood by the receiving node, this is not true for all protocols. With other protocols, the fall-back procedure may be sequential, e.g., from the third to the second to the first version, because no indication of the highest understood protocol version is provided by the receiving node. Hence, a falling-back procedure can require from one exchange, e.g., with MAP as described above, to a multiple of exchanges, e.g., where the protocol version level is sequentially reduced until compatibility is attained.
These falling-back procedures, although simple to implement, are unfortunately an uneconomical usage of network resources. Each message transaction 130-160 transmitted over the network consumes network bandwidth and therefore costs the cellular provider, which costs are naturally passed on to the cellular user. As is understood in the art, each communication over the network is charged by the network provider at a certain price per octet (byte) of data transmitted. Hence, reducing the number of data exchanges and time required to establish an internodal communication saves money. A system and method that can so reduce the number of typical fall-backs is, accordingly, desired.
It should further be understood that the situation illustrated in FIG. 1 is exacerbated as more updates of the MAP or other protocol become extant and the updates are issued more frequently. Furthermore, not only do different versions, i.e., major revisions of the standard, exist, but many incompatible variations, e.g., smaller changes to or enhancements of a major standard within a given Public Land Mobile Network (PLMN)) also permeate cellular networks. A variation (which may be realized by a protocol extension of a particular MAP version dialogue type) on one of the versions is typically implemented within one vendor""s network, which is usually updated all at once; nevertheless, multiple variations can cause incompatibilities. It would, therefore, be advantageous to utilize a system and method that can reduce the number of typical fall-backs by predicting the version (and even the variation) of MAP protocols capable of being used by a given node or entire PLMN for a given dialogue type.
The present invention addresses these (and other) deficiencies in conventional systems and methods by achieving the following (and other) objects of the invention:
A first object of the present invention is to reduce the number of communications required to negotiate between two nodes at a mutually-understood protocol level.
Another object of the present invention is to reduce the number of communications required to negotiate a mutually-understood protocol level between a first node and a second node by predicting at the first node the highest protocol level understood by the second node.
A further object of the present invention is to predict at the first node the highest protocol level understood by the second node by storing in a database table at the first node the most recently negotiated protocol level between the first node and the second node.
Yet another object of the present invention is to implement a protocol-predicting table that stores the protocol level understood for each dialogue type that has been negotiated with a given node.
Yet another object of the present invention is to implement a protocol-predicting table that stores the protocol level at both the nodal and the PLMN level.
A still further object of the present invention is to implement an elegantly simple system and method for reducing the number of communications required to negotiate a mutually-understood protocol level between two nodes that requires that only one table be stored in memory and accessed for each communication.
Another object of the present invention is to implement a simple system and method that requires no human operator intervention or interaction to function.
An additional object of the present invention is to implement a simple system and method that can be used permanently without regard to scheduled periods for protocol updating.
These and other objects of the present invention are achieved with a system and method for use in communications networks that enables a first node to initiate a communication with a second node using the most-advanced protocol version that the second node recognizes and understands. In an exemplary conventional system, dialogues across Public Land Mobile Network (PLMN) boundaries start with the highest Mobile Application Part (MAP) version available for the operation at the dialogue-initiating node. The fall-back procedure is then used to step down to the highest MAP version both nodes have in common. The present invention reduces or eliminates such fall-back procedures and therefore the number of costly messages required to communicate with distant nodes.
In accordance with the present invention, a database is maintained at each node in communications networks. The database is preferably composed of a single, persistent, and autonomously-maintained table. The table enables a first node to store, and subsequently retrieve for use, the latest protocol version that a second node is capable of understanding. Hence, once a communication has been established and the appropriate protocol version determined between the first and second nodes, the first node can use the determined protocol version to initiate subsequent communications. This eliminates the wasting of network signaling bandwidth that can otherwise occur.
In a preferred embodiment of the present invention, the communications networks are cellular networks and the signaling protocol is MAP. In this embodiment, the database table is further divided into different dialogues for each distant node. Accordingly, the first node will access the database by the address of the second node and then search for the desired dialogue that is affiliated with the second node in the table. The MAP version associated with the desired dialogue is then selected for initiating the desired dialogue with the second node.
In a further aspect of the invention, the table is refreshed periodically. It may be refreshed by deleting the entire table or individual entries once a protocol version has been extant within the table for a predetermined period of time. The table is thereafter gradually rebuilt (or the entries are gradually replenished) in the due course of accessing distant nodes and negotiating to determine the latest protocol version, such as described in connection with conventional systems and methods. In this manner, if the distant node has updated its protocol version, the table receives this updated protocol version information, enabling expedited internodal communications thereafter.
The above-described and other features of the present invention are explained in detail hereinafter with reference to the illustrative examples shown in the accompanying drawings. Those skilled in the art will appreciate that the described embodiments are provided for purposes of illustration and understanding and that numerous equivalent embodiments are contemplated herein.